Kassidy... I never got how anyone ever trusted her again. Just imagine a female freighter captain running supplies for Al Qaida, who somehow gets released from her time in Gitmo(six months?!) and goes to live on an army base with her boyfriend who's the colonel there..... yeah...
Sisko sure swept that one under the rug even as he went postal on Eddington.
Ro... yeah, she had very valid reasons for wanting to join up and ones I liked and by her nature she was never too apologetic. I was really disappointed we never got to see her on a guest role on DS9.
Kassidy Yates was a complete waste.. I couldnt stand listening to her talk. She was as whiny as Lois Griffin but no where near as good looking. Her being a Maquis collaborator is the biggest contradiction on DS9. I mentioned somewhere else that picard got nella darren, anij, crusher and Vash ... its ridiculous that they stuck Sisko with Yates.
The actress that played Ro Laren i think was initially approached for Kira's role but turned it down for some reason. I also heard they thought her defecting to the Maquis made her irredeemable which i thought was ridiculous (Same similar reason for not casting Robert Mcneil as Nick Locarno again but invented Tom Paris with the same back story... VERY WEAK)